Tested and in fine working condition. (https://www.glascol.com/GlasColItem.aspx?Item=100A+O412)

Glas-Col 3L Heating Mantle, model 0412, designed to meet your laboratory's temperature control needs. With a  3000 mL capacity, this mantle is ideal for various scientific applications requiring consistent heat.  Please note that the control is not included with this purchase.